1. Field of the Invention
The present invention relates generally to electronic circuits and systems. More particularly, the present invention relates to communications systems for transmission of digital data.
2. Background Art
Television news provides the public with coverage of interesting and relevant local news and events, assists law enforcement in finding and identifying crime suspects, and informs the public with early warning and ongoing coverage concerning emergencies and disasters such as fires, earthquakes, storms, terrorism, and other threats. Reliable transmission of these news stories can be vital for ensuring public safety. Besides news, television stations often provide entertainment, such as real time feeds of ongoing special events. Sporting games, parades, and live performances happening across the street or around the world are conveniently viewable at home thanks to these broadcasts. However, before these broadcasts reach their final destination at the viewer's television, they must first be recorded from cameras, often far away from the television studio. Thus, different techniques and devices have been developed to accomplish the task of transferring the camera footage to a desired location, usually a television station studio, to be disseminated to the wider public.
Electronic News Gathering (ENG) is an acronym that generally describes the process of a newscaster or television crew going out and covering a news story. One method used for video footage transfer in ENG is transmission through short-range direct line of sight microwaves. Generally, a vehicle such as a truck or van is specially modified with video equipment and a microwave transmission dish. The microwave transmission dish is often mounted on a telescoping mast that can rise about fifty feet into the air to achieve direct line of sight with a receive tower. The vehicle itself may also receive short-hop signals from, for example, portable cameras. Video production and editing equipment in the vehicle might be used to prepare video footage for broadcast. From that point, the edited video or raw footage may be sent via microwave transmission to a relay tower or directly to a central receive tower at the home studio. The relay towers might be strategically placed throughout the desired coverage area to allow greater reporting distance from the home studio.
Although microwaves work well when there is a clear and unobstructed path, if there is sufficient interference from, for example, adverse weather conditions, line of sight barriers, and interfering microwaves on nearby frequencies, microwave signal quality may degrade to the point of uselessness. In particular, the availability of microwave spectrum frequencies is extremely limited, requiring news agencies to carefully coordinate their microwaves not to interfere with each other. Regulations also limit the amount of microwave energy allowed for broadcast, further limiting microwave signal integrity. Thus, microwave transmission is not a completely reliable method of transfer, especially when operating far away from the central receive tower.
Another common method of transfer used by ENG is satellite communications. The specially modified vehicle previously mentioned might also be equipped with a satellite dish to supplant or complement the existing microwave transmission capabilities. The satellite dish is pointed skywards to a geostationary satellite, data is sent to the satellite, and the satellite relays that data back to the home studio. Thus, distance from the central receive tower is no longer a concern, as long as there is a clear path to the satellite. However, satellites suffer from similar transmission availability problems as microwave, such as limited satellite lifetime, limited frequency availability, interference, malfunction downtimes, and signal loss susceptibility in adverse weather conditions. Thus, satellite communications still inherit many unaddressed reliability concerns.
Accordingly, there is a need to overcome the drawbacks and deficiencies in the art by providing a way for video footage and other digital data to be reliably transferred from a remote location to desired destinations.